The present invention relates to a motor vehicle brake, in particular a motor vehicle brake that can be actuated in a combined hydraulic and electromechanical manner, having an actuator assembly comprising: a housing, an actuating element that is displaceable relative to the housing along a longitudinal axis for the hydraulic or electromechanical displacement of a brake lining, a motor drive, and a displacement mechanism, situated between the motor drive and the displaceable actuating element, for displacing the actuating element.
Motor vehicle brakes of this type are already known from the prior art.
The document WO 2008/037738 A1 describes a motor vehicle brake that can be actuated in a combined hydraulic and electromechanical manner. In a normal operating situation, i.e., during travel of the motor vehicle, this motor vehicle brake is hydraulically actuated in the customary manner. For activating a parking brake, the electromechanical actuating function is activated. In the process, an electric motor is actuated which drives a spindle-nut arrangement via a displacement mechanism having a gear system. The gear system has a self-locking design with a worm gear to prevent reduction of the parking brake action when the parking brake is activated. The special feature of the motor vehicle brake described in this prior art lies in the configuration of the spindle-nut arrangement, in which the rolling elements do not rotate, but instead are pretensioned via a spring. One disadvantage of this motor vehicle brake is that during an electromechanical actuation, a relatively large actuating travel must be overcome, which may take a very long time until the desired clamping action with the desired brake force is achieved. In addition, this design is relatively complicated.
In addition, the document WO 2009/046899 A1 describes a motor vehicle brake that is electromechanically actuatable. However, the electromechanical actuation takes place for activating the service brake function as well as for activating the parking brake function. For this reason, the gear system has a nonself-locking design. This motor vehicle brake has the advantage that no hydraulic system is necessary for its actuation, and instead the vehicle electrical system may be used to actuate the braking system. Since the gear system has a nonself-locking design, for locking the motor vehicle brake for the parking brake function, a separate locking device is provided in which a lever may be magnetically brought into a locking position. In this prior art, an application force reserve is also provided to compensate for settling processes on the brake linings due to cooling or the like after applying the brake in parking brake operation. Here as well, this motor vehicle brake has the disadvantage that a significant amount of time may elapse before the desired clamping action is achieved.